Alarm systems monitor sensors to determine the presence of people within a protected space. If the alarm system detects a breach of the protected space it will respond based on the state of the system. Possible system states include “disarmed”, “armed stay”, and “armed away.” If the system is disarmed it will not cause an alarm due to a breach of perimeter or interior sensors. If the system is armed stay, it will alarm due to a breach of the perimeter sensors, but not due to a breach the interior sensors. If the system is armed away it will alarm based on a breach of the perimeter or interior sensors. The state of the system is determined by the needs of the occupants of the premises. If all of the occupants are leaving the premises then the system should be armed away. If the occupants will be staying within the premises for an extended period of time then the system should be armed stay. For all other scenarios the system should be disarmed.
Problems arise when the system is not properly armed and disarmed. Typical problems include not disarming the system before the alarm sounds, arming away when occupants plan to stay within the protected space, and not arming the system when the premises are unoccupied. These are user created problems and as such, it is desirable to develop a system that will assist the end user with the arming and disarming operations.
Others have attempted to provide partial improvement by offering security systems that will assist the end user with arming and disarming. One such system, as described in U.S. Pat. No. 6,225,903, is armed and disarmed by the action of the deadbolt on the entry door. A switch is mounted in the doorjamb to detect when the bolt is extended into the jamb, i.e. locked. If the deadbolt is locked and the alarm system does not detect motion within a predetermined exit time, then the system will transition to the armed away state. If motion is detected then it will transition to the armed stay state. If the system is armed and the deadbolt is unlocked, then the system will transition to the disarmed state. A major drawback with this arrangement occurs when the door is forced open (i.e. a “kick-in” by an intruder) and the bolt disengages from the jamb switch without the use of a key. Although this is an unauthorized entry, the alarm system will disarm allowing the perpetrator full access to the premises.
An improvement to the '903 patent was set forth in U.S. patent application Ser. No. 10/462,449, now U.S. Pat. No. 6,963,280, which is owned by the assignee of this application. In that patent, a housing included a lock position detecting switch, adapted to detect the position of a lock mounted on a door as being either locked or unlocked, a door position detecting switch adapted to detect the position of the door as being either open or closed, and processing circuitry adapted to generate a security system disarm signal when (1) the position of the lock has transitioned from a locked state to an unlocked state, (2) the door is closed at the time that a predefined time period has elapsed since the position of the lock transitions from a locked state to an unlocked state, and (3) the door has been opened after that predefined time period has elapsed. The door entry device also has a data transmitter for sending the security system disarm signal to the control panel. An alarm signal is generated and transmitted to the control panel when the door is open at the time that the predefined time period has elapsed since the lock has transitioned to an unlocked state. The control panel prevents the security system from being disarmed when an alarm signal is received unless a user code is entered into the security system.
Although the invention in U.S. Pat. No. 6,963,280 significantly improved upon the prior art by providing protection against kick-in situations, it is nonetheless desired to provide an automatic arming/disarming solution by detecting the position of the doorlock alone, in particular by using a mechanism within or attached to the door itself, rather than the doorjamb as in the prior art patents described above.
Attempts have been made in the past to implement a magnetic sensor such as a reed switch mounted within the locking mechanism of the door, with a magnet mounted on a moving component of the lock mechanism, for sensing when a user has locked the door (and then arm the system) or has unlocked the door (and then disarm the system). These attempts have suffered from poor reliability, such as incorrectly sensing the position of the lock an unacceptable number of times, resulting in inadvertent arming and/or disarming of the system. In addition, it is believed that this type of device would result in poor security since intruders would be able to thwart an armed system by using a magnet on the outside of the door to create a magnetic field and as a result “trick” the mechanism into disarming the system.
The present invention addresses these as well as other problems in the prior art as set forth herein.